This invention relates generally to clutches, and in particular, to a mechanical drive clutch which reduces the backlash on forward and reverse shuttle operations.
Mechanical drive clutches are typically used to interconnect the transmission to the axle of a vehicle. There are two basic types of clutches, the friction clutch and the dog clutch. The friction clutch provides high performance at differential speed engagement with little or no noise during shuttle operations. However, friction clutches must be designed to hold full engine power through the clutch. As a result, the engagement of the plates must be modulated in some fashion in order to assure adequate plate life. Consequently, the costs associated with the design and manufacture of friction clutches are significantly greater than those associated with dog clutches.
A dog clutch typically includes a pair of jaws directed towards each other for connecting and disconnecting driving and driven parts, for example, in a motor vehicle between the engine and the transmission. When attempting to connect the driving and driven parts of a vehicle, the jaws of the dog clutch rotate until each tooth on one jaw finds a corresponding gap on the mating jaw. When the gap is found, the two jaws engage each other allowing power to be transmitted therethrough.
In order to allow the jaws to engage at differential speeds, the width of each jaw tooth on one jaw must be less than the corresponding gap or seat on the mating jaw. This gap is often referred to as the backlash in the dog clutch. During any forward or reverse shuttle, each jaw tooth must rotate through the corresponding gap to drive the forward side or to drive the reverse side of a corresponding tooth on the mating jaw. This free spin condition results in a load band when the jaw teeth on one jaw engage the forward or reverse side of the corresponding jaw teeth on the mating jaw. The noise associated with the load band is highly undesirable.
Therefore, it is a primary object and feature of the present invention to provide a dog clutch which greatly reduces or eliminates the backlash on forward and reverse shuttle operations.
It is a further object and feature of the present invention to provide a dog clutch which allows for engagement of mating jaws at various speeds.
It is a further object and feature of the present invention to provide a dog clutch which smoothly connects and disconnects the driving and driven parts of a vehicle.
It is a still further object and feature of the present invention to provide a dog clutch which is simple and inexpensive to manufacture.
In accordance with the present invention, a mechanical drive clutch for mounting on a rotatable shaft is provided. The clutch includes a drive gear rotatably received on the shaft. The drive gear has a plurality of gear teeth of a predetermined arcuate length which are circumferentially spaced about the shaft and which project in a first direction parallel to the longitudinal axis of the shaft. A sleeve is slidably mounted on the shaft for rotational movement therewith. The sleeve includes a plurality of gear engagement recesses therein of an arcuate length greater than the predetermined arcuate lengths of the gear teeth. The sleeve is movable between a first retracted position wherein the gear teeth are disengaged from the gearing engagement recesses and a second engaged position wherein each gear tooth is received within a corresponding gear engagement recess. plurality of anti-backlash elements are mounted within the sleeve and movable within between a first position wherein each of the anti-backlash elements extend into a corresponding gear engagement recess in order to compensate for the difference in the arcuate lengths of each gear tooth and its corresponding gear engagement recess, and a second retracted position.
The sleeve may include a plurality of pockets. Each pocket communicates with a corresponding gear engagement recess and slidably receives a corresponding anti-backlash element therein. A plate, axially spaced from the sleeve, is fixed to the shaft for rotational movement therewith. Springs are partially received within each corresponding pocket such that the first end of each spring engages the plate and a second end engages a corresponding anti-backlash element in a corresponding pocket so as to urge the anti-backlash element into a corresponding gear engagement recess. A biasing structure may also be provided for urging the sleeve into the retracted position.
It is contemplated that the drive gear be rotatable about the shaft and include a radially outer edge having a plurality of drive teeth thereon. It is also contemplated that each anti-backlash element terminate at a generally flat outer surface directed towards the drive gear and lying in a plane perpendicular to the longitudinal axis of the shaft. Each anti-backlash element may include a chamfered edge extending from the end surface thereof.
In accordance with a further aspect of the present invention, a mechanical drive clutch for mounting on a rotatable shaft is provided. The clutch includes a drive gear rotatably received on the shaft. The drive gear has a plurality of gear teeth circumferentially spaced about the shaft and projecting in a first direction parallel to a longitudinal axis of the shaft. A sleeve is slidably mounted on the shaft for rotational movement therewith. The sleeve includes a face surface directed towards the drive gear and a plurality of gear engagement recesses therein for receiving corresponding gear teeth. The sleeve is movable between a first retracted position wherein the gear teeth are disengaged from the gear engagement recesses and a second engaged position wherein each gear tooth is received within a corresponding gear engagement recess. A plurality of anti-backlash elements are slidably mounted within the sleeve and movable between a first position wherein each anti-backlash element extends into and partially fills a corresponding gear engagement recess and a second retracted position.
The sleeve may include a plurality of pockets. Each pocket communicates with the corresponding gear engagement recess and slidably receives a corresponding anti-backlash element therein. A plate, is affixed to the shaft for rotational movement therewith. A plurality of springs are partially received within corresponding pockets such that the first end of each spring engages the plate and the second end engages the corresponding anti-backlash element in the corresponding pocket so as to urge the anti-backlash element into a corresponding gear engagement recess. A biasing structure may also be provided for urging the sleeve into the retracted position.
It is contemplated that the drive gear include a radially outer edge having a plurality of drive teeth thereon. It is also contemplated that each anti-backlash element terminates at a generally flat outer surface directed towards the drive gear and lying in a plane perpendicular to the longitudinal axis to the shaft. Each anti-backlash element includes a chamfered edge extending from the outer surface thereof. In accordance with a still further aspect of the present invention, a clutch is provided for mounting on a rotational shaft extending on the longitudinal axis. The clutch includes a rotatable drive gear received on the shaft. The drive gear is driven about the shaft by an external source and has a gear tooth projecting therefrom in a direction parallel to the longitudinal axis. The gear tooth is defined by a leading surface and trailing surface interconnected by a face surface. A sleeve is slidably mounted on the shaft for translating rotation of drive gear to the shaft. The sleeve includes a gear engagement recess therein. The gear engagement recess is defined by a first tooth receiving portion and a second backlash portion. The sleeve is movable between a first retracted position wherein the gear tooth is disengaged from the gear engagement recess and a second engaged position wherein the gear tooth is received within a corresponding gear engaging recess. A pop-up jaw is mounted within the sleeve and movable between a first position wherein the pop-up jaw extends into the backlash portion of the gear engagement recess and a second retracted position.
It is contemplated that the sleeve includes a pop-up jaw retention structure for retaining a portion of the pop-up jaw therein. The sleeve also includes an inner surface which forms a slidable interface with the shaft and an outer peripheral surface. The hydraulic pressure source controls movement of the sleeve in the retracted and engaged position.